Slagging furnace



Oct. 24, 1944. A. c. FOSTER 2,360,863

SLAGGING FURNACE Filed Sept. 5, 1942 3 Sheets-Sheet 1 & INVENTOR filBERT C FOSVZ'R Q" Y 5 M/ ATTORN EY Oct. 24, 1944. A. c. FOSTER SLAGGING FURNACE Filed Sept. 5, 1942 v 3 Sheets-Sheet 3 ATTORNEY Patented a. 24, 1944 SLAGGING FURNACE Albert 0. Foster, Westileld, N. 3., asslgnor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application September 5, 1942, Serial No. 457.512

19 Claims.

furnaces, molten slag deposited on the floor flows continuously thereover to a discharge opening through which the slag flows from the furnace. The refractory lining of the floor is protected from excessive heat by water tubes usually closely spaced and connected into the boiler circulation. The water tubes are, in turn, protected from the excessive temperature and the molten slag by a covering or "blanket" which is usually of a heat resistant material such as chrome plastic. It is necessary, however, that means be employed to insure retention of the heat resistant material over the tubes against the tendency of the molten slag to wash the covering away.

The present invention provides means for preventing erosion of the furnace floor tube covering by the flow of molten slag to the slag discharge opening in the floor by providing a protective coating of slag over said covering.

The features and advantages which characterize the invention will be apparent from the following description when considered in connection with the accompanying drawings forming a part thereof, and in which:

Fig. 1 is a partial vertical sectional view of a continuous slagging type furnace embodying the invention;

Fig. 2 is a vertical sectional view taken on the line 22 of Fig. 1;

Fig. 3 is a vertical sectional view taken on the line 33 of Fi i;

Fig. 4 is a partial plan view of a continuous slagging type furnace embodying the invention taken on the line 4-4 of Fig. 2;

Fig. 5 is a somewhat enlarged sectional view taken on the line 5-5 of F18. 2;

Fig. 6 is a vertical sectional view taken on the line 6-6 of Fig. 5;

Fig. 7 is a somewhat enlarged sectional view taken on the line 1-1 of Fig. 3, and

Fig. 8 is a. vertical sectional view taken on the line 8& of Fig. "I.

Like characters of reference refer to like parts throughout the several views.

Referring to the form of the invention shown in Fi s. 1 to 8 of the drawings, reference character l0 designates generally a furnace of a steam generator having positioned in the front wall ll thereof one or more burners I! for burning a slag forming fuel. The furnace, as shown, has substantially horizontal refractory floor portions I3 and it, side walls I! and I. and a rear wall H. A slag discharge opening or slot it extends across the width of the furnace floor at right angles to the side walls and midway between the front and rear furnace walls. The refractory floor portions are lined with closely spaced parallel'water tubes l9 and 20, which as shown, extend upwardly from the floor and respectively line the front wall II and rear wall I! and form part of the circulatory system of the steam generating unit. The side walls l5 and it are lined respectively by water tubes 2| and 22 also connected into the circulatory system of the steam generator. The tubes l9 and 20 are curved adjacent the opening it and extend into the throat of the opening. Tubes l9 and 20 are bent away from the throat below the curved surface to promote disengagement from the surface of the tubes in the throat of the slag flowing into the reservoir.

The portions of the tubes l9 and 20 lining the refractory floor portions l3 and I4 are covered by a protecting blanket of chrome plastic or other suitable refractory material, the blanket covering the tubes I 9 being designated by the reference numeral 23 while the covering for the tubes 20 is designated by the numeral 24.

In order that the blanket covering on the tubes I9 and 20 will not be eroded by the flow of slag thereover as it passes to the discharge opening i8, and the coverings 23 and 24 will be maintained in position over the tubes l9 and 20 respectively against the drag exerted by the flowing slag, water-cooled dam means are provided having a height greater than the thickness of the coverings 23 and 24 so that a protective coating of slag will be formed over the blanket coverings. The water-cooler dam means in the form of the invention shown in Figs. 1 to 8, comprises spaced tubes through which cooling fluid flows in series. As shown, the dam structure on the floor portion It comprises a tube 25 which extends transversely of the tubes 20 at a point adjacent the curved portion thereof. The tube 25 rests upon the tubes 20 and is connected at one end through a connecting tube 25' to a cool water inlet. At the opposite end, the tube 25 is in communication with a similar tube 26 through a connection 21. The tube 26 extends parallel to the tube 25 in a plane vertically inclined thereto in a direction toward the discharge opening and is connected to an outlet through a connecting tube 28' and a valve 20. Tubes 25 and 26 are held in spaced relationship to one another by means of the spacing member 28' which is positioned between the tubes and extends paral lel to the axis thereof. The member 28 which is Substantially square, is positioned with diagonally opposite edges adjacent the periphery of the tubes and is secured to the tubes by welding.

Mounting means are provided whereby the tubes 25 and 26 are mounted on the tubes 20 and the relationship of the dam tubes 25 and 26 and the floor tubes 20 is maintained despite movement of the tubes due to expansion and contraction or drag exerted thereon by the flow of slag to the sla discharge opening, or other causes. The mounting means comprise bridge members 29 which bridge the space between adjacent tubes 20 at spaced intervals transversely of the floor substantially beneath the tube 26. The bridge members are welded or otherwise secured to the tubes 20. A mounting member 30 adapted to embrace at its upper end a portion of the circumference of the tube 26 at the side and bottom thereof extends downwardly therefrom. The member 30 is secured to the tube by welding and is recessed transversely thereof at its lower end so that a substantial part 3I thereof rests upon the bridge member 29, while,

a projection 32 extends downwardly beyond the bridge 29 and in spaced relationship thereto. In this manner, the tube 26 is supported on the bridge member 29. The tube 25, which rests upon the tubes 20, has an L-shaped member 33 attached thereto, one leg 34 embracing the bottom and one side of the tube while the other leg 35 extends at substantially right angles to the leg 34 and is substantially coextensive with the width of the bridge member 29. Both legs of the L-shaped member are spaced from the member 29. A slot is thereby formed by the members and 33 which is of a greater dimension than the bridge member 29. The member 33, as shown, has a chamfer 36 on both sides and is of such a thickness that it may move freely in the space between the tubes 26 at the top thereof. The blanket covering 24 of refractory, which is of a thickness substantially equal to the diameter of the tube 25, extends upwardly over the tubes 25 and 26 and thence downwardly in a thin layer over the curved portion of the tubes 20 in the opening I 8. A spillway 31 is formed in the dam structure by bending a portion of the tube 26 downwardly into substantially the horl-- zontal plane of the tube 25.

In the form of the invention shown in Figs. 1 to 8, the fly ash is returned to the furnace onto the bottom portion I4 by fiy ash returning mechanism 38, shown diagrammatically, which is positioned adiacent the side wall l5 and rear wall H of the furnace. fly ash causes more slag to flow over the floor portion I4 than the 11001 portion I3, so that it is necessary to have a dam of greater height thereon than on the floor portion I3. The height of the dam is governed by the angle of inclination of the tube 26 in relation to the tube 25. As shown, the water-cooled dam means positioned in the floor portion I3 forms a dam of lesser height than the dam on the floor portion I4.

The water-cooled dam means on the floor portion I3 comprises a return bend tube having two legs 39 and 40 positioned in substantially the same horizontal plane and extending transversely of the tubes I9. The legs 39 and 40 of the return bend tube are supported by the tubes I9 and are held in position thereon by means of tie members 4I which extend between the legs 39 and 40 at spaced intervals and project downwardly into the space between the tubes I9. The

Burning and melting of the tie members are recessed at the opposite ends thereof to embrace the circumference of a portion of one side and the bottom of the legs 39 and 40 to which they are secured by Welding or by any other desirable means. The tie members have a slot 42 therein through which a bridge member 43 is threaded. The bridge member 43, which is similar to the bridge members 29 between the tubes 20, bridges the space between adjacent tubes I9 and is secured at opposite ends to these tubes. The slot 42 is of a greater length and a greater width than the member 43 so that the tie member may freely move either longitudinally or transversely with respect to the bridge member. The lower portion of the tie members is chamfered at 44 and it is of such thickness that movement in the space between the tubes I9 is permitted. The leg 40 of the return bend tube is connected through a connecting conduit 45 to a cool water inlet, while the leg 39 is connected to an outlet through a conduit 46 and a valve 41. The protecting blanket 23 which is of a thickness substantially equal to the diameter of the return bend tube, extends upwardly over andcovers the legs 39 and 40 of the return bend tube and then downwardly over the curved portion of the tubes 20 in the opening I 8. The thickness of the covering over the curved portions of the tubes is less than that over the straight portions thereof.

In operation, molten slag collects on the furnace floor portions I3 and I4 and flows over the protecting blankets 23 and 24 on said floor portions respectively toward the opening I 8. The quantity of slag flowing over the floor portion I4 is normally greater than can be accommodated by the spillway 31 because the returned fly ash is burned or melted on the same side of the furnace. Since the slag flow is thereby retarded, a coating of slag is formed over the protecting blanket 24 which prevents the blanket from washing away. As the furnace continues to operate, the coating of slag becomes greater in thickness until it flows over the water-cooled dam. Erosion of the blanket over the tubes 25 and 26 is prevented by thecooling effect of these tubes which is maintained by flowing cool water from the cool water inlet through the connecting tube 25', tube 25, connection 21, then into the tube 26 and through the tube 26 into the connecting tube 26, and through the valve 28 to the outlet. As the temperature in the furnace varies, the tubes 25 and 26 expand and contract moving independently of the tubes 20. When the tubes 25 and 26 expand axially, the support 30 and L-shaped member 33 move longitudinally of the bridge member 29, and when the tubes 20 expand and contract axially the bridge member 29 is permitted movement within the slot formed by'the supporting member 36 and the L-shaped member 33.

The slag flowing over the covering 23 on the floor portion I3 toward the opening I8 flows into contact with the water-cooled dam and upon continued operation of the furnace, a covering of slag is formed over the blanket 23, the thickness of which is determined by the height of the dam. The slag covering on the blanket 23, which is of a plastic material, prevents the blanket from becoming washed away. After a covering of slag of predetermined thickness is formed, further molten slag flows over the dam and into the slag discharge opening I8. Since the dam is cooled by cool water flowing through the legs 39 and 40 of the return bend tube of the dam, from a source of cool water flowing through the connecting conduit 4'5, leg 40 and leg 39 to an outlet through the conduit 45 and valve 41 resulting in a complete circulation of cool water through said tube, erosion of the covering 23 over the return bend tube is prevented. Axial expansion and contraction of the tubes 39 and 40 due to temperature changes in the furnace causes the tie-members II to move longitudinally of the bridge members 43. Upon axial movement of-the tubes IS, the bridge member 43 moves longitudinally in the slot 42 f the tie members.

It will be understood that changes may be made in the form, location and relative arrangement of the several parts of the apparatus disclosed without departing from the principles of the invention. Accordingly, the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

1. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor. a fluid cooled dam on the floor comprising cooling tubes disposed in substantially the same horizontal plane and extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent the cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means comprising a member secured to the cooling tubes and extending into said space between the water tubes said member having a slot therein through which the bridge member extends, the slot being of such dimensions that the mounting means and the bridge member may have limited movement in relation to each other, and a layer of refractory material extending over the cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

2. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor. a flu d cooled dam on the floor comprising substantially parallel spaced cooling tubes disposed in substantially the same horizontal plane and extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adja- 7 cent the cooling tubes and bridging thespace between adjacent water tubes, mounting means said space between the water tubes, the mounting means being arranged torest on the bridge member, said means being constructed to form a guideway around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

4. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube and extending into said space between the water tubes, the mounting means being of a dimension to permit lateral movement thereof in said space in relation to the floor and arranged to rest on the bridge member, said means being constructed to form a guideway comprising a member secured to the cooling tubes maintaining said tubes in spaced relationship with one another and extending into said space between the water tubes said member having a slot therein through which the bridge member extends, the slot being of such dimensions that the mounting means and the bridge member may have limited movement in relation to each other, and a layer of refractory material extending over the cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water-tubes being of a th ckness less than the height of the dam.

3. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube and extending into around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge memberin relationship to each other, and a layer of refractory material extending over said cooling tube v and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

5. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube and extending into said space between the water tubes, the mounting means being arranged to rest on the bridge member, said means being constructed to form a guideway aroundthe bridge member, the guideway being of a dimension to permit a limited relative movement of the bridge members and the mounting member longitudinally of the floor and r to limit the movement of said cooling tube and the water tubes toward and away from each other, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

6. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a, fluid cooled dam on the floor comprising a plurality of cooling tubes disposed in spaced vertical planes and extend ng transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tubes and extending into said space between the water tubes. the mounting means being arranged to rest on the bridge member. said means being constructed to form a guideway around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over th water tubes being of a thickness lessthan the height of the dam.

7. A furnace having a floor including a slag discharge opening substantially intermediate the ends of said floor and extending substantially from side to side thereof, a plurality of water tubes extending longitudinally of the floor at substantially right angles to the opening at opposite sides thereof, fluid cooled dams on the floor extending transversely thereof adjacent the opening and on each side thereof, said dams comprising at least one cooling tube, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube and extending into said space between the water tubes, the mounting means being arranged to rest on the bridge member, said means'being constructed to form a guideway around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

8. A furnace having a floor including a slag discharge opening intermediate the ends of the furnace and extending substantially from side to side thereof, floor tubes extending on the floor at substantially right angles to the opening at opposite sides thereof and projecting downwardly thereinto over the opposite sides thereof, fluid cooled dams on the floor extending transversely thereof adjacent the opening and on each side thereof, the dam on one side of said opening comprising cooling tubes disposed in substantially the same horizontal plane and extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes. mounting means secured to said cooling tubes and extending into said space between the water tubes, the mounting means being of a dimension to permit lateral movement thereof in said space in relation to the floor and having a slot therethrough through which the bridge member projects, the slot being of a. dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, the dam on the other side of the opening comprising substantially parallel tubes extending transversely of the Water tubes and through which a' cooling medium is circulated, one of said tubes being disposed in a higher horizontal plane than the other, and in a vertical plane nearer the opening than said other tube, means for holding said cooling tubes against movement in relation to each other, bridge members secured to the water tubes adjacent the cooling tubes on said other side of the opening and bridging the space between the upper portion of the adjacent Water tubes, mounting means secured to the cooling tubes on said other side of the opening and extending into said space between the water tubes, the mounting means on the tubes on said other side of the dam comprising one member secured to said other cooling tube and having a portion extending along the bottom surface of the bridge member and in movable relationship thereto and another member secured to said one cooling tube having a portion extending along the top surface of the bridge member in slidable relationship therewith, said one member and said other member each having a portion adjacent opposite sides of the bridge member, said portions being spaced from each other a distance sufficient to permit a, limited movement of the bridge member upon longitudinal movement of the water tubes, and a layer of refractory material extending over the cooling tubes on both sides of the slag discharge opening and over the water tubes in front of the dams the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

9. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising cooling tubes disposed in substantially the same horizontal plane and extending transversely of the water tubes adjacent the opening, bridge members secured to the Water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tubes and extending into said space between the water tubes, the mounting means being of a dimension to permit lateral movement thereof in said space in relation to the floor and having a slot therethrough through which the bridge member projects, the slot being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

10. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising substantially parallel tubes extending transversely of the Water tubes and through which a cooling medium is circulated, one of said tubes being disposed in a higher horizontal plane than the other,-means for holding said cooling tubes against movement in relation to each other, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tubes and extending into said space between the water tubes, the mounting means being arranged to rest on the'bridge member, said means being constructed to form a guideway around the bridge member, the guideway being of a dimension to permit'a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractor material over the water tubes being of athickness less than the height of the dam.

11. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising substantially parallel tubes extending transversely of the water tubes and through which a cooling medium is circulated, one of said tubes being dissaid means being constructed to form a guideposed in a higher horizontal plane than the other and in a vertical plane nearer the open ing than said other tube, means for holding said cooling tubes against movement in relation to each other, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tubes and extending into said space between the water tubes, the mounting means comprising one member secured to said other cooling tube and having a portion extending along the bottom surface of the bridge member and in movable relationship thereto and another member secured to said one cooling tube having a portion extending along the top surface of the bridge member in slidable relationship therewith, said one member and said other member each having a portion adjacent opposite sides of the bridge member, said portions being spaced from each other a distance sufficient to permit a limited movement of the brdige member upon longitudinal movement of the water tubes, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being ofa thickness less than the cooled dam on the floor comprising substantially parallel tubes extending transversely of the water tubes and through which a cooling medium is circulated, one of said tubes being disposed in a higher horizontal plane than the other and in a vertical plane nearer the opening than said other tube, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tubes and extending into said space between the water tubes, the mounting means being of a dimension to permit lateral movement thereof in said space in relation to the floor and comprising one member secured to said other cooling tube and having a portion extending along the bottom surface of the bridge member and in movable relationship thereto and another member secured to said one cooling tube having a portion extending along the top surface of the bridge member in slidable relationship therewith, said one member and said other member each having a portion adjacent opposite sides of the bridge member. said portions being spaced from each other a distance suflicient to permit a limited movement of the bridge member upon longitudinal movement of the water tubes, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

13. A furnace having a floor including a slag discharge opening, a plurality of spaced water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between adiacent water tubes, mounting means secured to said cooling tube and extending into the space between the water tubes, the mounting means being arranged to rest on the bridge member,

way around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

14. A furnace having a fioor including a slag discharge opening, a plurality of spaced water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising substantially parallel tubes extending transversely of the water tubes and through which a cooling medium is circulated, one of said tubes being disposed in a higher horizontal plane than the other, means for holding said cooling tubes against movement in relation to each other, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between adjacent water tubes, mounting means secured to said cooling tubes and extending into the space between the water tubes, the mounting means being arranged to rest on the bridge member, said means being constructed to form a guideway around the bridge member, the guideway being of a dimension to permit a limited movement of the mounting means and bridge member in relationship to each other, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

15. A furnace having a floor including a slag discharge opening, a plurality of spaced water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising substantially parallel tubes extending transversely of the water tubes and through which a cooling medium is circulated, one of said tubes being disposed in a higher horizontal plane than the other and in a vertical plane nearer the opening than said other tube, means for holding said cooling tubes against movement in relation to each other, bridge members secured to the water tubes adjacent said cooling tubes and bridging the space between adjacent water tubes, mounting means secured to said cooling tubes and extending into the space between the water tubes. the mounting means comprising one member secured to said other cooling tube and having a portion extending along the bottom surface of the bridge member and in movable relationship thereto and another member secured to said one cooling tube having a portion extending-along the top surface of the bridge member in slidable relationship therewith, said one member and said other member each having a portion adjacent opposite sides of the bridge member, said portions being spaced from each other a distance sufficient to permit a limited movement of the bridge member upon longitudinal movement of the water tubes, and a layer of refractory material extending over said cooling tubes and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the darn.

16. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge memberssecured to the water tubes adiacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube arranged to rest on the bridge member, said means being constructed to provide stops which limit relative movement of the bridge members and the mounting means axially of said water tubes, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

17. A furnace having a floor including a slag discharge opening, a plurality of spaced water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between adjacent water tubes, mounting means secured to said said cooling tube arranged to rest on the bridge member, said means being constructed to provide stops which limit relative movement of the bridge members and the mounting means axially of said water tubes, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

18. A furnace having a floor including a slag discharge opening, a plurality of water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between the upper portion of adjacent water tubes, mounting means secured to said cooling tube arranged to rest on the bridge member, said means being constructed to provide stops which limit relative movement of the bridge members and the mounting means axially of said water tubes and limit the amount the cooling tube and mounting means may move away from the bridge members, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

19. A furnace having a floor including a slag discharge opening, a plurality of spaced water tubes extending longitudinally of the floor, a fluid cooled dam on the floor comprising at least one cooling tube extending transversely of the water tubes adjacent the opening, bridge members secured to the water tubes adjacent said cooling tube and bridging the space between adjacent water tubes, mounting means secured to said cooling tube arranged to rest on the bridge member, said means being constructed to provide stops which limit relative movement of the bridge members and the mounting means axially of said water tubes and limit the amount the cooling tube and mounting means may move away from the bridge member, and a layer of refractory material extending over said cooling tube and the water tubes in front of the dam, the layer of refractory material over the water tubes being of a thickness less than the height of the dam.

ALBERT C. FOSTER. 

